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Strange question about salsa

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40hz:
I've seen that happen too. Funny how salsa will do that - but the metal staple in a teabag won't. Weird huh?

Here's an article by Adrian Popa (Staff Optical/Microwave Physics, Hughes Research Laboratories) on it happening with grapes:

http://www.madsci.org/posts/archives/dec97/882909591.Ph.r.html

... There are two general classes of antennas, metallic conducting antennas and dielectric antennas that concentrate electromagnetic fields. The common antennas most people are familiar with are antennas made from conducting wires and rods such as the rabbit ears on indoor TV antennas or the multirod TV antennas on millions of roof tops. Dielectric antennas include various geometric solids including cylinders, spheres and plastic focusing lenses.

Non conducting dielectric materials are used for microwave cooking ware because they are relatively transparent to microwave energy. Also dielectric heating of food, particularly the water molecules in food, is the key principle used in microwave cooking.

Dielectric spheres one or more wavelengths in diameter form a special class of microwave antenna structure. When a dielectric sphere is immersed in a microwave field the spheres concentrate the electric field lines along an axis as shown in Figure A. If the sphere is slightly elongated, the field will usually align with the longest axis. This is exactly what water filled grapes (which are one or two wavelengths in diameter) will do in a microwave oven. The concentrated microwave field inside the grapes quickly heats the grapes to a high temperature after only 10 seconds of heating. ...

I put two grapes with their stem holes tightly together and the pair of grapes form a larger more efficient dipole like antenna as the microwave energy field flows between the two coupled grapes. I believe this is why the coupled grapes are much hotter after 10 seconds of heating than single grapes are.

Finally, I slightly separated the stem holes of the grape pairs by about one millimeter. As the grapes are heated each grape emits a jet of steam toward the other grape and the concentrated microwave fields from the spheres reach more than 3000 volts exciting the steam into a plasma state as shown in Figure B. The plasma forms a short circuited conductor between the dipoles and we get the arching in the region of steam between the arrows shown in Figure B. When the grapes have expelled their steam pressure I found that the plasma extinguishes and the arc goes out.

This explanation is based on spheres filled with pure water and we know that the grape juice is acidic not just pure water. A more complex reaction is occurring within the grapes. However, the external resultant arcing would probably be about the same for both cases.

I said in the beginning that this is a complicated experiment with a complicated answer. It would take some expensive microwave equipment and time to study the arcing grapes in more detail in the laboratory. I hope this helps answer some of your questions.
--- End quote ---

Must have been a slow day over at Hughes Research. :P

40hz:
If you wish to avoid problems with salsa in the microwave, respect the 'No Dancing' warning on the inside of the door.
-cranioscopical (March 02, 2010, 05:01 PM)
--- End quote ---

So that's why I couldn't get that lemon merengue pie recipe to work in the microwave!
 ;D

Shades:
...but my "special" cake (Dutch recipe) cannot stop raggeaton dancing...  ;)

Deozaan:
So why would you want to microwave salsa? Isn't it supposed to be served chilled, or at least only room temperature?

JavaJones:
As you'll note from the article on grapes, it's the separation that causes the "spark" (or plasma as he says). Do these sparks occur only on the surface of your salsa, or do they appear to be inside too? Is this chunky salsa (e.g. fresca) by chance? If so perhaps the chunks are creating shapes in the surface that result in small gaps and produce a similar effect to the grapes. Note that I think the composition of the material matters, as in the case of the grape with a large proportion of water (and sugars?). So perhaps the salsa's composition has similarly spark/plasma-friendly characteristics...

- Oshyan

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